1. Field of the Invention
The present invention relates to a storage system and a control method for the storage system.
2. Description of the Related Art
In organizations such as governments, corporations, and universities, for handling a large amount of data varying in type, a storage system of a relatively large size is used for data management. Such a storage system is configured by a disk array device, for example. The disk array device is configured by a large number of storage devices arranged in an array, and provides a storage area based on, for example, RAID (Redundant Array of. Independent Disks). Any physical storage area provided by a group of storage devices as such is formed thereon with at least one or more logical volumes, which are provided to a host computer, more in detail, to a database program operating on the host computer. The host computer (hereinafter, simply referred to as “host”) can perform data writing/reading to/from the logical volumes with transmission of any predetermined command.
The data to be managed in the organizations increases in amount day by day, and thus a storage system may be provided with a large storage area in expectation of a demand increase in the future. The issue here is that, the unit price of a storage device indeed tends to be reduced year by year, but purchasing a large number of storage devices to be ready for a demand increase in the future as such may result in excessive upfront investment. Therefore, when the need arises for any new storage area, purchasing any appropriate number of storage devices will favorably reduce the cost of the storage system.
On the other hand, if a storage area satisfying only the current demand is available for use, any new demand cannot be immediately met, thereby reducing the usability of the storage system. In consideration thereof, Patent Document 1 (JP-A-2005-31929) describes a technology of virtualizing, for management, storage areas of storage devices in a storage system, and using the virtualized storage areas as needed.
Moreover, for using any existing storage resources with good efficiency, Patent Document 2 (JP-A-2005-107645) describes a technology with which one storage control device captures thereinto a logical volume(s) in another storage control device, and makes a host believe that the logical volume(s) are of its own. In this previous technology, the correlation is controlled between a logical volume(s) being a connection source and a logical volume(s) being a connection destination, and in accordance with an access made to the logical volume (s) being the connection source, another access is made to the logical volume(s) being the connection destination.